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Answers to Exercises

๐Ÿ“˜ Chapter 1: Functions

Easy

1. (a) 5    (b) -7    (c) -15

2. (a) Domain \(x \ge -5\), range \(y \ge 0\)    (b) Domain \(x \neq 3\), range \(y \neq 0\)    (c) Domain \([-2,2]\), range \([-4,0]\)

3. (a) Yes    (b) No    (c) Yes

Medium

4. (a) 74    (b) 52    (c) \(25x - 6\)

5. (a) \(f^{-1}(x) = \frac{2x - 4}{3}\)    (b) \(f^{-1}(x) = \sqrt{x + 1}\)

6. Vertex \((3,0)\), intercepts \((0,6)\), \((6,6)\)

7. Domain \([9, \infty)\)

Hard

8. Proof using definition of inverse and composition

9. \(f^{-1}(x) = \frac{ax + b}{cx - a}\) (self-inverse)

10. (a) Yes (linear, \(m \neq 0\))    (b) \(C^{-1}(c) = \frac{c - 200}{1.5}\)    (c) 100 minutes

๐Ÿ“˜ Chapter 2: Quadratic Functions

Easy

1. (a) \((x - 3)^2 + 1\), min = 1 at \(x = 3\)    (b) \(-2(x - 2)^2 + 3\), max = 3 at \(x = 2\)    (c) \(3(x + 2)^2 - 5\), min = -5 at \(x = -2\)

2. (a) 49, two real    (b) 0, one repeated    (c) -23, no real

3. (a) \(x < 1\) or \(x > 3\)    (b) \(-4 \le x \le 2\)

Medium

4. \(2(x - 2)^2 - 3\), min = -3 at \(x = 2\)

5. (b) Max area 100 mยฒ at \(x = 10\) (square)    (c) \(5 \le x \le 15\)

6. \(k < -2\) or \(k > 6\)

7. \(c = -1\)

Hard

8. (b) \(k = 1\)

9. (a) \(m^2 + 4m - 12 < 0\)    (b) \(-6 < m < 2\)

10. (a) 6000 subscribers    (b) Rs 64,000    (c) \(x = 2\) and \(x = 10\)    (d) \(2 < x < 10\)

๐Ÿ“˜ Chapter 3: Equations, Inequalities and Graphs

Easy

1. (a) \(x = 2, 8\)    (b) \(x = -5, 4\)    (c) \(x = -\frac{4}{3}, 4\)

2. (a) \(x < -10\) or \(x > 2\)    (b) \(-1 \le x \le \frac{7}{3}\)

3. Roots at 2, 4, 6

Medium

4. \(x = -1\) or \(x = 4\)

5. \(0.5 \le d \le 3.5\) km

6. \(x < 1\) or \(3 < x < 5\)

7. \(\frac{2}{3} \le x \le 8\)

8. \(k = -2\)

Hard

9. \(x = 1, 2, 3, 4\)

10. (a) \(k = -2\)    (c) \(x \le 1\) or \(3 \le x \le 5\)

11. (b) \(2 \le x \le 5\) or \(x \ge 8\)    (c) same, since \(C(x) \le 10 \iff (x-2)(x-5)(x-8) \le 0\)

๐Ÿ“˜ Chapter 4: Factors of Polynomials

Easy

1. (a) -8    (b) 1

2. \(P(1) = 0\) โœ“

3. (a) \((x - 1)(x - 2)(x - 3)\)    (b) \((x + 1)(x - 1)(x + 2)\)

Medium

4. \(-\frac{5}{4}\)

5. \(k = 2\)

6. (a) \((x + 3)(x + 2)(x - 1)\)    (b) \((x - 2)(2x + 3)(x - 1)\)

7. (a) \(x = 1, 2, 4\)    (b) \(x = -1, 2, 3\)

Hard

8. \(a = 1, b = -14\), factorised: \((x - 2)(x + 4)(x - 1)\)

9. Proof using Factor Theorem: \(P(2) = 2^n - 2^n = 0\)

10. (a) \((x - 3)(x - 4)(x - 5)\)    (b) \(x = 3, 4, 5\)    (c) \(x > 5\) or \(3 < x < 4\)    (d) height = 3 cm

๐Ÿ“˜ Chapter 5: Simultaneous Equations

Easy

1. (a) \(x = 5, y = 2\)    (b) \(x = 3, y = 2\)

2. (a) \((1,1)\) and \((2,4)\)    (b) \((-1,3)\) and \((2,6)\)

3. \((1, \frac{5}{2})\) and \((5, \frac{1}{2})\)

Medium

4. \((1,1)\) and \((5,9)\)

5. \(k = 1\)

6. 6 books, 6 pens

7. \(m < -6\) or \(m > 2\)

Hard

8. \(m = 0\) (tangent is horizontal), \(c = 1\)

9. (a) 20 of A, 30 of B    (b) 30 of A, 20 of B

10. \(c = 5\)

๐Ÿ“˜ Chapter 6: Logarithmic and Exponential Functions

Easy

1. (a) 5    (b) 4    (c) -2

2. (a) \(\log_3 35\)    (b) \(\log_4 1 = 0\)

3. Graphs are reflections across \(y = x\)

Medium

4. (a) \(x = 3\)    (b) \(x = 4\)    (c) \(x = 2\)

5. 5

6. Approximately 1,314,860 tourists

7. \(x \approx 3.32\)

Hard

8. \(x = 4\) (\(x = -2\) is invalid since log undefined for negative)

9. Proof using change of base

10. (a) 700    (b) \(\approx 609\)    (c) 200    (d) asymptote \(y = 200\), y-intercept \((0,700)\)

๐Ÿ“˜ Chapter 7: Straight Line Graphs

Easy

1. (a) \(m = 4, c = -3\)    (b) \(m = -\frac{2}{5}, c = 2\)    (c) \(m = \frac{3}{4}, c = 2\)

2. (a) \(y = 2x\)    (b) \(y = -\frac{2}{3}x + \frac{5}{3}\)

3. (a) \((3,4)\), length = 10    (b) \((5,3)\), length = 10

Medium

4. (a) \(y = 2x - 8\)    (b) \(y = 3x - 11\)

5. \(y = -x + 10\)

6. Fixed fee = Rs 40, rate = Rs 35 per km

7. \(a = e^2 \approx 7.39, n = 1.5\)

Hard

8. \(m = 2, c = -3\)

9. \(m = -\frac{1}{3}, c = -\frac{1}{3}\)

10. (a) \(V = e^9 e^{-0.15t} \approx 8103 e^{-0.15t}\)    (b) \(\approx\) Rs 8103    (c) \(\approx\) Rs 3835

๐Ÿ“˜ Chapter 8: Circular Measure

Easy

1. (a) \(\frac{\pi}{6}\)    (b) \(\frac{3\pi}{4}\)    (c) \(\frac{5\pi}{4}\)

2. (a) \(30^\circ\)    (b) \(120^\circ\)    (c) \(225^\circ\)

3. (a) \(2\pi\) cm    (b) \(10\pi\) cmยฒ

Medium

4. (a) \(8\pi\) cm    (b) \(48\pi\) cmยฒ    (c) \((8\pi + 24)\) cm

5. (a) 30 cm    (b) 360 cmยฒ

6. (a) \(\frac{2\pi}{3}\)    (b) \(10\pi\) m    (c) \(75\pi\) mยฒ

7. 1 radian

Hard

8. \(r = \frac{P \pm \sqrt{P^2 - 16A}}{4}\)

9. \(\theta = \frac{4}{3}\) radians

10. (a) \(\frac{\pi}{2}\) rad    (b) \(4\pi\) cm    (c) \(8\pi\) cmยฒ    (d) \(8\pi\) cm

๐Ÿ“˜ Chapter 9: Coordinate Geometry of the Circle

Easy

1. (a) \((x - 2)^2 + (y - 3)^2 = 16\)    (b) \((x + 1)^2 + (y - 5)^2 = 36\)    (c) \(x^2 + y^2 = 10\)

2. (a) Centre \((3, -2)\), \(r = 4\)    (b) Centre \((-4, 1)\), \(r = 5\)

3. Inside (distance squared = 8 < 9)

Medium

4. Centre \((3, -2)\), \(r = 5\)

5. Centre \((-5, 3)\), \(r = 7\)

6. \((2 + 2\sqrt{2}, 3 + 4\sqrt{2})\) and \((2 - 2\sqrt{2}, 3 - 4\sqrt{2})\)

7. \(k = -1 \pm \sqrt{17}\)

Hard

8. \(y = -\frac{4}{3}x + 10\)

9. (a) Yes (distance from centre to line = 4 < 8)    (b) \((15 \pm 4\sqrt{3}, 15.25 \pm 3\sqrt{3})\)    (c) \(c = -5\) (tangent condition)

10. \(m < -2\) or \(m > 2\)

๐Ÿ“˜ Chapter 10: Trigonometry

Easy

1. (a) \(\frac{\sqrt{3}}{2}\)    (b) \(\frac{\sqrt{2}}{2}\)    (c) \(\frac{1}{\sqrt{3}}\)    (d) \(\sqrt{2}\)

2. (a) Amp = 3, Period = \(180^\circ\)    (b) Amp = 4, Period = \(720^\circ\)

3. (a) \(60^\circ, 120^\circ\)    (b) \(120^\circ, 240^\circ\)

Medium

4. Principal axis \(y = -1\), max at \((0,1)\) and \((360^\circ,1)\), min at \((180^\circ,-3)\)

5. \(120^\circ, 300^\circ\)

6. (a) Amp = 200, Principal axis = 500    (b) 700    (c) 12 hours

7. Proof: LHS = \(\frac{2\sin x}{1 - \cos^2 x} = \frac{2\sin x}{\sin^2 x} = \frac{2}{\sin x} = 2\cosec x\)

Hard

8. \(x = 30^\circ, 150^\circ, 270^\circ\)

9. Proof: LHS = \(\frac{1 - \sin/\cos}{1 + \sin/\cos} = \frac{\cos - \sin}{\cos + \sin}\)

10. (a) 33 m    (b) 3 m    (c) 24 minutes    (d) \(t = 2\) minutes, 10 minutes

๐Ÿ“˜ Chapter 11: Permutations and Combinations

Easy

1. (a) 120    (b) 72    (c) 15

2. 120

3. 120

Medium

4. 120

5. 1680

6. (a) 495    (b) 210    (c) 245

7. 1680

Hard

8. 50,400

9. \({}^{5}P_2 \times {}^{10}P_3 = 20 \times 720 = 14,400\)

10. 1190

๐Ÿ“˜ Chapter 12: Series

Easy

1. (a) 26    (b) 185

2. (a) 64    (b) 60

3. \(x^3 + 6x^2 + 12x + 8\)

Medium

4. \(a = 6, d = 4\)

5. 765

6. 32

7. 80

8. 805 (approx)

Hard

9. (a) \(r = 3\)    (b) \(a = 2\)    (c) \(S_6 = 728\)

10. 15

11. \(k = 2\)

๐Ÿ“˜ Chapter 13: Vectors in Two Dimensions

Easy

1. (a) \(3\mathbf{i} + 4\mathbf{j}\)    (b) \(-2\mathbf{i} + 5\mathbf{j}\)    (c) \(-7\mathbf{j}\)

2. (a) 5    (b) 10    (c) \(\sqrt{2}\)

3. (a) \((7, -2)\)    (b) \((-3, -4)\)    (c) \((6, -9)\)

Medium

4. (a) \((6, 8)\)    (b) 10    (c) \((\frac{3}{5}, \frac{4}{5})\)

5. \(k = -\frac{1}{2}\)

6. (a) \((5, 1)\)    (b) \(\sqrt{26}\) m/s    (c) \(\tan^{-1}(\frac{1}{5}) \approx 11.3^\circ\)

7. \(PQ = QR = 2\sqrt{5}\) (isosceles)

Hard

8. \(C = (6.5, 9)\) or \((\frac{13}{2}, 9)\)

9. (a) N \(14.0^\circ\) W (or \(104^\circ\) from east)    (b) \(\approx 193.65\) km/h

10. Proof using vector addition of midpoints gives equal and opposite vectors

๐Ÿ“˜ Chapter 14: Calculus (Differentiation and Integration)

Easy

1. (a) \(12x^3\)    (b) \(5x^4 + 6x^2 - 7\)    (c) \(2\cos 2x\)

2. 8

3. (a) \(x^4 + C\)    (b) \(x^3 + x^2 - 5x + C\)    (c) \(-\frac{1}{3}\cos 3x + C\)

4. 9

Medium

5. (a) \(e^x(x^2 + 2x)\)    (b) \(\frac{1 - x^2}{(x^2 + 1)^2}\)    (c) \(\frac{2x}{x^2 + 1}\)

6. \(y = 2x - 6\)

7. \((3, -1)\) is minimum, \((1, 3)\) is maximum

8. \(\frac{dr}{dt} = \frac{1}{8\pi}\) m/min \(\approx 0.0398\) m/min

9. (a) \(\frac{14}{3}\)    (b) 1

Hard

10. \(f(x) = x^3 + x^2 + 1\)

11. (a) \(v = 3t^2 - 12t + 9\), \(a = 6t - 12\)    (b) \(t = 1, 3\)    (c) \(s(1) = 6, s(3) = 2\)    (d) 6 m

12. \(\frac{4}{3}\) square units

13. Maximum volume = 125 cmยณ

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